Thoughts on Classifying Teas

This will be a quick post lacking the photos and reference links in most of my diatribes…

The Tea Institute works on a semester lecture cycle, where our new students (prospective researchers) join one of our 3 tea ceremony clubs (Chinese, Japanese, or Korean), learn a ceremony up to a point of proficiency, and can then test into the Institute (the ‘Tea Specialist Examination’).

I run the lecture / lesson cycle for Chinese Tea Ceremony, and for the last 6 semesters have been refining my lectures from ~2ish hour rambles (painful) to 45min soliloquies (almost beautiful).

For the last few weeks I have been lecturing on Tea Production Methodologies and classification; these are topics that merit their own 8 week lecture cycle, but we distill them into 1 lecture per class which for the most part works quite well. As a derivative of the standard Chinese classification system we use percentage oxidation to determine primary classification of tea – these are the ranges listed below:

  1. Green (0 – 6%)
  2. White and Yellow (0 – 10%)
  3. Mainland Oolongs (25 – 70%)
  4. Taiwanese Oolongs (15 – 90%)
  5. Sheng Pu’er (0 – 20%)
  6. Shou Pu’er (~0 – 25%) & other Post Fermentation Teas
  7. Chinese Red Tea (~100%) & non-traditional teas

Yet, these distinctions are not without their problems; all classification is at some level arbitrary! (and it’s impossible to determine actual level of oxidation of any specific tea without Gas or Liquid Chromatography – so don’t believe anyone who gives you a specific oxidation percentage!)

These ranges aren’t perfect, and its probable that you wouldn’t think too highly of a tea at the minimum or maximum oxidation of its class; but they are good generalizations. There are exceptions to every rule, but you should still know the rule.

White, Yellow, and Green tea all have overlapping ranges for percentage oxidation; a first pass at this level of analysis would have you believe these teas should be categorized together. That could work – many in China do classify White and Green tea together.

At the Institute, we don’t. We use a 2 stage process of classification: Percentage Oxidation, and Processing Methodology. Thus, White Tea goes through a withering before ShaQing (deactivation of the oxidizing enzyme), while Yellow tea goes through a process creatively known as Yellowing (withering in the presence of excess moisture).

Sheng Pu’er and Shou Pu’er follow the same example: same range of oxidation, yet a difference in processing leading to distinct classification. This is all well and good as I would hate to ache for a Sheng flavor profile only to brew a Shou.

This is an intuitive and working system.

Where this system of classification fails is in the cup. We don’t classify teas by flavor profile, yet the point of tea is appreciation through consumption (sweeping over generalization, but don’t care this post).This means that classification is disjoint from our reason for classification; selecting teas with the flavor profile we desire.

Thus, when oxidation and processing are no longer the most important factor in determining flavor profile, which is quite rare, we are left with a cup that resides “out of character”.

We have a policy in the tea house to force our members (including myself) to Identify a tea by taste alone before we will tell them what it is. I started thinking about this classification problem when I misidentified a thermos brewed YueGongBai, a white tea, as a DianHong, a Yunnan red tea. [Thermos brewing is another great habit; you can learn a lot about a tea by ‘stress testing’ it (holding a tea at a very high temperature until it reaches maximum solubility of the water)].

The new, and dedicated student was quick to jump on my mistake; he thought it was quite heinous to mistaste a white for a red, and in other circumstances he would be right! This is not a mistake I would have made from a Gaiwan brew.

What might pardon me from sin? YueGongBai is made with Yunnan DaYe cultivar, the same cultivar used to make (most) Pu’er and DianHongs. When brewed in a thermos, the flavor attributes generated by the DaYe cultivar far outweighs the flavor attributes modulated by processing. That is to say, I identified the cultivar!

Did I miss identify the tea? Yes. But, I must question, was this a personal fault, or a fault of classification? – comment below.

On another note:
The Institute has been overrun with all of our new projects and research this semester, and I have personally been running a work marathon juggling my start up, the Institute, research, okapi hunting, and classes (not to mention competition fencing and climbing). And sleeping. Need sleep….

I promise more posts with more of a research focus soon.
[unless all you want chaxi photos, but you’d need to tell me that in the comments]

– Jason

Migrated Comments

Grant Mueller

Do you think it would be worthwhile to do a comparative brewing of YueGongBai and DianHong: in a thermos, in a gaiwan, and a ping mei bei (competition set)? I’m interested in studying the flavor attributes of the DaYe cultivar.

Jason's Reply


Yes, that is one way to do it!

The most common tea produced with DaYe cultivar is of course Pu’er, and if you wanted to tease out the effects of Pu’er processing, YueGongBai and some DianHongs would be a good way to do it.

I wouldn’t bother with the PingBiBei trial though, it overlaps both the Gaiwan in tea to water ratio and the thermos in stress test.

All the Best,

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